Influence of transition metal inclusion on the phase transformations and thermodynamics of Se80Te20 alloy

Abstract

This study explores how incorporating transition metals (TMs) influences the phase transformation and thermal behaviour of Se₈₀Te₂₀-based alloys, formulated as Se 80-x Te 20 TM x (x = 0, 2; TM = Co, Fe, Cu, Ni). Thermal analyses were conducted using Differential Scanning Calorimetry (DSC) under controlled heating conditions to extract thermodynamic parameters such as specific heat ( Cₚ ), entropy (Δ S ), enthalpy (Δ H ), and Gibbs free energy (Δ G ). Including TMs alters the heat capacity response near the glass transition, indicating changes in configurational freedom and structural rigidity. A systematic correlation between Cₚ variation and heating rate was observed across all samples, revealing the dynamic thermophysical nature of these chalcogenide alloys. Thermodynamic signatures inferred from Cₚ – T curves and entropic analysis exhibit second-order-like characteristics in the sense of Ehrenfest's framework. These findings provide a detailed understanding of how transition metal doping tunes the thermal stability and glass-forming ability of Se Te systems. • Cobalt enhances thermal stability and raises crystallization enthalpy. • Nickel increases network rigidity, reducing vibrational entropy modes. • Copper lowers Tg, increases free volume and structural disorder. • Iron improves thermal uniformity and stabilizes amorphous network. • Transition metals modify Cp, ΔS, and ΔG significantly. • STNi exhibits minimal Cp/T 3 peak, confirming rigid structure. • STCu enhances atomic fluctuations with moderate thermodynamic stability. • Entropy and enthalpy trends correlate with dopant coordination. • DSC confirms altered glass transition dynamics by each dopant.